How to use solar power?
If you are going to use solar energy, you must learn the principles of solar cells, which can also be called PV cells (abbreviation for photovoltaic cells) or photoelectric cells. Many small and huge devices contain such sells. Their active component is silicon, in fact – melted sand.
When the sunlight strikes upon a solar cell, electrons (they are red) are knocked freely. They start moving toward the treated front surface (it is dark blue). Thus, we observe a kind of electron imbalance between the back and front. If we connect the two surfaces with a wire, the positive and negative sides will surely produce a current of electricity between them.
Such individual solar cells are brought together in a PV module. Such modules are usually ordered in an array. Then the arrays are set on specific tracking devices aimed to follow sunlight throughout the day.
A PV system makes the conversion of solar energy into solar electricity, which may be freely used by any electrical home appliances. It includes the following subsystems:
- PV Devices
- BOS, or Balance of System
The task of PV Devices is to generate solar power via the conversion of sunlight into direct-current (or widely known DC) electricity.
The Load is just a device, which uses the electricity one way or another. Your vacuum cleaner is an excellent example of a load.
The BOS includes all the necessary equipment between the load and PV devices. The Balance of System consists of the structures for the montage of PV devices, the power cooling equipment for the conversion of the DC electricity to AC, or alternating-current, to be utilized by the load, and batteries you need to store the PV generated electricity.
- Montage Structures: The montage systems that are necessary to integrate the PV array with the structural systems inside your home.
- Array DC Disconnect: It halts the flow of electricity from your PV array. It is very significant for the maintenance and troubleshooting of the system.
- Charge Controller: It is necessary for the battery bank monitoring to prevent it from the overcharge.
- Battery Bank: This is a group of batteries connected together with wires. They store the energy, which has been produced by PV arrays, for future use.
- System Meter: With it, you are able to monitor the status and – what is more important – performance of your PV system.
- Main DC Disconnect: It halts the flow of electricity to the inverter from the battery bank.
- Solar power inverter: As you’ve already known, the PV arrays create the direct current (DC) power. The function of the inverter is to convert the DC power into the standard alternating current (AC) one, which may be easily used in your home.
- AC Breaker Panel: You already have it in your house! This breaker panel functions as a router for the power from the PV array and for the utility to be connected to your internal electrical system.
- Electric Meter: This gauge measures the total amount of electricity either produced by or supplied to your home. Owing to it, you may calculate your electricity bills for each month.
- Backup Generator: It produces the AC power, which is converted to DC power with the inverter for its future deposit in the battery bank. It may be utilized when the PV devices cannot produce electricity for a prolonged period of time.
Solar Panels. How powerful are they?
The effectiveness of a solar panel as well as the energy it produces depend on the number of climatic, weather, and geographic factors. Rainless climates are perfect for solar panels. Also, they are able to produce more energy in case when they are exposed to the straightforward sunlight in the clear sky. But there is a great difference between the power a solar panel achieves and the power it can deliver. Of course, it’s possible to work out how powerful a solar panel would be. For instance, if a panel is rated at 180 watts it’ll perform up to such a level in the brightest sunlight that would generate 1,000 W/m2. But, if you don’t live right on the equator line, your solar panel is not going to get such a quantity of the sunlight. Thus, the simplest method to work it out is to bring to light the number of the peak hours of the sun in your location for each day. A peak sun hour here should be one hour of 1,000 W/m2 of sunlight. After that, you can multiply easily the watt rating of your solar panel by the number of peak hours of the sun for your local area. You must also remember that sun hours undergo the natural changes by season, so the lowest ones are in winter.
The Variety of Solar Panels
Now, there are 3 main types of solar photovoltaic panels that can be bought by any homeowner:
- Monocrystalline modules,
- Polycrystalline modules,
- Thin-film modules.
The manufacturing process for monocrystalline solar cells includes the applying of a single crystal core of silicon. The silicon core is cut into some thin wafers in order to make the solar cell.
Polycrystalline solar cells are manufactured from a great number of silicon crystals. Such solar cells are shaped when the molten silicon is streamed into a mold so that to form a bar. After the process of cooling, the silicon bar is sliced to form the end-product – the solar cell.
If we consider the last type, thin-film solar cells, they are usually manufactured from amorphous-silicon alloys brought in very thin layers onto a glassy or metal ground stuff called a substrate. In contrast to the polycrystalline and monocrystalline modules, a lot of thin-film modules are flexile enough, so they can be utilized in a variety of applications.
Comparison of Solar Panels
There are several factors that determine the type of solar panels (monocrystalline, polycrystalline, or amorphous ones). They are the physical structure, the type of the practically used silicon, efficiency, and, for sure, cost.
This type utilizes the solar cells that have been made from a single large crystal of great purity, cut from bars. Such cells are the most effective type of solar panels. The minus is that at the same time they are the most expensive ones. Their performance is a bit better in the conditions of low light (but be careful and don’t swallow different fraudulent advertising baits). The average overall efficiency makes about 12-15%. The warranty for such panels is 20-25 years. Usually, they are blue-grey in their color. Also, they have a pretty uniform consistence.
Their structure is crystallized, as you can see it from their name. They are considered to be the industrial standard, as in general these panels are about twice as effective as amorphous cells. As a rule, the effectiveness ratings range from 12-16%. Nowadays, the most common type of solar panels is the polycrystalline one. These panels are a bit less effective than the single crystal, but if they are set into a framework with about 35 other cells, the practical difference measured in watts per square meter, or even foot, is not so much.
Their main active component is loosely structured and non-crystallized silicon sprayed onto the ground stuff. They are generally called “thin film” panels. These panels are known for their surface covered with parallel lines. They are usually the cheapest, but they are also the least effective (7 per cent efficiency only) and they have the shortest shelf life and practical utilization (about five years). Therefore, it is better for them to be commonly used for a small building or for a vehicle.
Other Types of Panels
Concentrating PV Solar Panels – These types contain a mirror or a lens to concentrate the solar energy on an individual set of solar cells. Theoretically, these panels will be more effective, as by concentrating the solar energy fewer solar cells are necessary to produce the same amount of energy. A particular type of plastic lens, or a Fresnell lens, is applied by many concentrating panels to focus the solar energy. One more type of concentrating solar panel – a Heliotube – uses a number of hollows that track the sun’s movement to provide greater solar effect on the solar cells. Concentrating solar panels lower the quantity of PVs needed to create electricity, and also lower the amount of space necessary for a PV facility. Their main minus is that they depend on the straightforward light only in the production of electricity, while stand-alone PV panels have the possibility to utilize both straightforward and diffuse light. Many regions don’t get enough straightforward light during the year for such systems to make such types of panels rather practical. One more minus is the complexity of their construction. It is rather difficult to build and install such systems if we compare them with conventional PV panels. Also, concentrating panels are much more heavier than conventional PV ones, and they have a number of non-fixed parts. This fact makes them more susceptible to bad luck than conventional panels. These panels are utilized in living solar PV systems on rare occasions.
Group III-V Technology Panels – Now there is a plenty of research aimed at the creation of very upgraded solar panels and cells. Solar cells created owing to the advanced technologies are usually called Group II and IV cells. Such complicated solar cells utilize dozens of materials with very high conversion efficiency to grab more segments of the light spectrum. A characteristic material used in the technology we’ve mentioned above is gallium arsenide, which may be matched with any other materials to create the types of semiconductors, which may respond to various types of solar energy. The use of current by such technologies is limited because of their very high cost, though they are believed to be very effective. Nowadays, they are applied in space industry only. They are utilized for the construction designs of different satellites and lunar rovers, for instance, the Mars rovers. The effectiveness of Group III-IV solar panels makes about 25%.
So, if you are an average homeowner, probably you’ll want to come alone with either monocrystalline or polycrystalline solar panels. For sure, your choice will depend on the price. If you have a south facing roof with enough roof space, it will be the best option for most household PV applications. In this case we aren’t trying to advise thin-film amorphous panels. Such solar panels must be much larger to give the same amount of the electric output from other panels. What is more, there isn’t enough space on most roofs to accumulate as much energy as you need.
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